Pulp-bleaching method and apparatus



March 17, 1925. 1,529,919

A. F. RICHTER PULP BLEAGHING METHOD AND APPARATUS Filed March 6, 1922Patented Mar. 17, 1925.

AUGUST F. RICHTER, OF WATERTOWN, NEW YORK, NEERING AND MANUFACTURINGCOMPANY, OF

PORATION OF NEW YORK. A

WATERTOWN, NEW YORK, A COR- PULP-BLEACHING METHOD AND APPARATUS.A

Application tiled March 6, 1922. Serial No. 541,463.

To all whom it may concern. y Be it known that I, AUGUST F. RICHTER, acitizen of the United States of America, and a resident of Watertown,county .of Jefferson, and State of New York, have 1nvented certain newand useful Improvements in Pulp-Bleaching Methods and Apparatus, ofwhich the following is a full and clear specification. Y

This invention is designed to provide a simple and eicient method andapparatus for carrying out the pulp-bleaching method disclosed" inHeiskan'en Patent No. 1,27*?,- 926, dated Sept. 3, 1918, and the speclalobject of the invention is to so construct the apparatus as to reduce toa minimum the consumption of steam, bleach and power, as more fullyhereinafter set forth.

It will be understood, however, that this invention is not exclusivelyconfined to the carrying out of the method disclosed in the aforesaidpatent.

In the drawing- Fig. 1 is a view partly in side elevation and partly invertical section, taken on the line 1--1 of Fig. 2;

Fig. 2 is a miniature plan view of a series of units of my apparatus; i

Fig. 3 is a detail vertical sectional view through the air ring ornozzle.

Referring to the drawing, 5 designates the main tank of each unit and 6two supplemental conduits or receptacles arranged at opposite sides ofthe main receptacle, all three receptacles being circular incrosssection. The supplemental receptacles 6 are much smaller indiameter than the main receptacle and they serve to convey 'the pulp andbleach to the upper end of the main receptacle and empty the samethereinto, the upper ends of these uptakes 6 entering the mainreceptacle at opposite sides through openings therein, these openingsbeing located at or near the upper end of the main receptacle.

The bottom of the main tank is tapered downwardly to a throat 7 leadinginto a short horizontal conduit 8 which forms a part of the uptakes 6,each end of this conduit being connected to the adjacent lower end ofone of the uptakes by a curved upwardly-tapering conduit 9. Extendingthrough stuliing-boxes 10 in the walls of the curved conduits 9 is ashaft 11 mounted in suitable bearings 12 and driven by Suitable fast andloose pulleys 13. Axed. to the shaft 11 is a air of screw-impellers 14which fit the conduit 8 and are arranged at opposite sides .of thethroat 7. These impellers are arranged to oppose each other, so as toimpel the pul outwardly in opposite directions from t e throat 7, sothat in the operation of the apparatus these screw-impellers will drawequal amounts of pulp down through throat 7 and for-ce it outwardly andupwardly into the uptakes, thereby delivering it back into 'the mainreceptacle at the upper ends thereof. This arrangement of opposedimpellers and two uptakes enables me to move the pulp without end-thruston the impeller shaft, since the two impellers balance each other so faras end-thrust is concerned. This overcomes anobjection found to exist inthe apparatus shown in the Heiskanen patent, since in the Heiskanenstructure there was liability that the end-thrust on the impeller wouldunstepthe shaft. In this way, I am enabled to work unusually thick pulp,i. e., pulp having a very high percentage of fiber to water, therebygreatly economizing in steam, power and bleach.

The main receptacles are located side by side, as shown in Fig. 2, andare connected by overflow tubes or troughs 15, in each of which works ascrew 16, these screws all being fastened to a common shaft 17 driven byany suitable power mechanism. As in the Heiskanen method, the pulp iskept in constant circulation in each unit (a unit being composed of amain\.tank and two supplemental uptakes) and at the same time a quantityof the pulp equal to the quantity fed into the first tank is carriedover into the next adjacent tank. The screws or Ipropellers 16 ensure aconstant and uniform feed of the pulp from unit to unit and enables meto handlethick pulp. It is 0bvious that if on'e unit contains a littlemore than the next one, the discharge-screw thereof will immediatelycorrect the situation by carrying a little more over into the next unit,thereby ensuring substantially the same level of pulp in all the mainreceptacles to thus ensure a uniform distribution throughout the system.

Each of the curved conduits 9 is connected to the vertical part of theuptake .ASSIGNOR TO STEBBINS ENGL by means of an air-ring 18 which ishol-y low and is adapted to be connected to a compressed-air supplythrough an inlet 19. The interior of the ring 18. is connected to asupplemental air channel 20 by means of air-holes 21, associated witheach of -which is a needle-valve 22 by which the amount of airentering-the hole' 21 is regulated. The annular channel 20 is connectedto the interior of the uptake by upwardlyinclined nozzle-passages 23,whereby one or more upwardly-directed'compressed-air currentsv isdirected into the upgoing mass of pulp. These upwardly-flowing aircurrents tend to lift the stock and thus Iassist the impellers greatlyin keeping it .moving This air 'also cuts down friction by giving thestock a sort of air cushion to travel on and "thus enables me to movethe heaviest stock at a .minimum consumption of power. And, furthermore,the chemical reaction that takes place when the calcium chloride may beemployed.

liquor of the bleach comes in contact with cellulose or pulp is greatlyaided by this aeration, thereby speeding up the bleaching action.

It will be understood, of course, that any other fluid, such as oxygen,chlorine gas or any other liquid or gas which will assist in moving aswell as bleaching the stock I do not desire to be understood as limitingmyself to the precise details of construction and arrangement shown, asvariamade 4without departingv from the spirit and scope of my inventionandimprovements. I therefore reserve -the' right to. all such variationsand modifications as properly fall within the scope of my' invention andimrovements and as set forth. in` the terms of the following claims.

f What I claim is:

1. ln an apparatus for bleaching pulp, a main-tank, a pair of conduitsarranged at- 'opposite sides of the' main tank having their upper endsdischarging into the main tank, a horizontal conduit arranged across thelower, open end of the main tank and arranged to discharge into thelower ends ofthe conduits, and a shaft extending horizontally throughsaid horizontal conduit and provided with a pair of. opposed propellersarranged at opposite sides of said open end of the main tank, for thepurpose set forth.

2. In a. pulp-bleaching apparatus em bodying an uptake for conveying thepulp upwardly, means for propelling the pulp, and means for introducinga bleaching-accelerating fluid under pressure into said uptake, thislatter means embodying a plurality of nozzles arranged around the uptakeand directed upwardly to thereby introduce the luid into the mass ofpulp in the form of aplurality of upwardly-directed streams, for thepurpose set forth;

3. In an apparatus for bleaching pulp, a

'series of tank-units,I each comprising a mam vtank and a palr ofsupplemental or uptake.

sure into said uptake at the lower endthereof,.said latter meansembodying a nozzle extending only to the interior surface of the uptakeso that the Huid will 1ubricate and thus reduce the friction of theIupgoing pulp. tions and modifications therefrom may be 5. The methodherein described ofY bleaching pulp consisting lin maintaining-anupgoing continuously-moving` mass. ofpulp l 'andhwater and bleachingagent,'and contin-` uously introducing under pressure .into'the' lowerend of said upgoing column of pulp "a bleaching accelerating fluid, thisfluid being delivered at a point between thejpulp and the enclosing wallof the uptake, for the purpose set forth.

6. The method herein described of bleaching paper pulp consisting ininjecting under pressure a plurality of jets of bleachl ing-acceleratingfluid directly into a mass of mixed pulp and bleaching liquor to therebynot only agitate the mass to thus intimately mix thebleaching-accelerating uid with the pulp and the bleaching liquor, butalso to assist in moving the same.

ln testimony whereof l hereunto aiiix my signature. v

AUGUST F. RICHTER.

